package java111;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Scanner;

public class Day13 {
    // https://ac.nowcoder.com/acm/contest/11215/A
    public static void main1(String[] args){
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        while(n-- > 0){
            int sum = in.nextInt();
            int score = in.nextInt();
            String str = in.next();
            int res = 0, count = 0;
            for(int i = 0; i < str.length(); ){
                if(str.charAt(i) == 'W'){
                    while(i < str.length() && str.charAt(i) == 'W'){
                        count++;
                        i++;
                        if(count >= 3){
                            res += score;
                        } else {
                            res += 1;
                        }
                    }
                } else {
                    count = 0;
                    res -= 1;
                    i++;
                }
            }
            System.out.println(res);
        }
    }


    // https://www.nowcoder.com/practice/b56799ebfd684fb394bd315e89324fb4?tpId=196&tqId=37149&ru=/exam/oj
    public int maxLength(int[] arr) {
        // write code here
        int res = 0;
        HashMap<Integer, Integer> hashMap = new HashMap<>();
        int left = 0, right = 0;
        for (; right < arr.length; right++) {
            if (!hashMap.containsKey(arr[right])) {
                hashMap.put(arr[right], 1);
            } else {
                res = Math.max(res, right - left);
                while (arr[left] != arr[right]) {
                    hashMap.remove(arr[left]);
                    left++;
                }
                left++;
            }
        }
        res = Math.max(res, right - left);
        return res;
    }


    //https://ac.nowcoder.com/acm/problem/222104
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] arr = new int[26];
        int[] arr1 = new int[26];
        char[] temp = new char[n];
        char[] res = new char[n];
        String str = in.next();
        for (int i = 0; i < str.length(); i++) {
            arr1[str.charAt(i) - 'a']++;
            arr[str.charAt(i) - 'a']++;
        }
        Integer[] tmp = new Integer[arr.length];
        for(int i = 0; i < tmp.length; i++){
            tmp[i] = arr[i];
        }
        Arrays.sort(tmp, (a, b) -> {return b-a;} );
        if (tmp[0] > (n + 1) / 2) {
            System.out.println("no");
            return;
        } else {
            System.out.println("yes");
        }
        for (int j = 0; tmp[j] != 0; j++) {
            for (int i = 0; i < arr1.length; i++) {
                if (arr1[i] == tmp[j]) {
                    temp[j] = (char) (i + 'a');
                    arr1[i] = -1;
                    break;
                }
            }
        }

        for (int i = 0, j = 0; j < arr.length && tmp[j] != 0; j++) {
            while (tmp[j]-- > 0) {
                res[i] = temp[j];
                i += 2;
                if (i >= res.length) {
                    i = 0;
                    while (i < res.length && res[i] != '\u0000') {
                        i++;
                    }
                }
            }
        }
        System.out.println(new String(res));
    }
}
